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At least 307 records · Page 17Linked to original sources
PubMed2006

Establishing interspecific mosaic genome lines between Drosophila ananassae and Drosophila pallidosa by means of parthenogenesis.

Strong sexual isolation exists between the closely related species Drosophila ananassae and D. pallidosa, but there is no obvious post-mating isolation; both sexes of the hybrids and their descendants appear to be completely viable and fertile. Strains exhibiting parthenogenesis have been derived from wild populations of both species. We intercrossed such strains and established iso-female lines after the second generation of parthenogenesis. These lines are clones, carrying homozygous chromosomes that are interspecific recombinants. We established 266 such isogenic lines and determined their genetic constitution by using chromosomal and molecular markers. Strong pseudo-linkage was seen between loci on the left arm of chromosome 2 and on the right arm of chromosome 3; the frequency of inheriting the two chromosome regions from the same species was significantly larger than expected. One possible cause of pseudo-linkage is female meiotic bias, so that chromosomes of the same species origin tend to be distributed to the same gamete. But this possibility is ruled out; backcross analysis indicated that the two chromosome regions segregated independently in female hybrids. The remaining possibility is elimination of low-fitness flies carrying the two chromosome regions from different species. Thus, genetic incompatibility was detected in the species pair for which no hybrid breakdown had previously been indicated. The 'interspecific mosaic genome' lines reported here will be useful for future research to identify genes involved in speciation and phenotypic evolution.

Animals↗
PubMed2000

Microsatellite variation in populations of Drosophila pseudoobscura and Drosophila persimilis.

We have isolated, characterized and mapped 33 dinucleotide, three trinucleotide and one tetranucleotide repeat loci from the four major chromosomes of Drosophila pseudoobscura. Average inferred repeat unit length of the dinucleotide repeats is 12 repeat units, similar to D. melanogaster. Assays of D. pseudoobscura and populations of its sibling species, D. persimilis, using 10 of these loci show extremely high levels of variation compared with similar studies of dinucleotide repeat variation in D. melanogaster populations. The high levels of variation are consistent with an average mutation rate of approximately 10(-6) per locus per generation and an effective population size of D. pseudoobscura approximately four times larger than that of D. melanogaster. Consistent with allozymes and nucleotide sequence polymorphism, the dinucleotide repeat loci reveal minimal structure across four populations of D. pseudoobscura. Finally, our preliminary recombinational mapping of 24 of these microsatellites suggests that the total recombinational genome size may be larger than previously inferred using morphological mutant markers.

Animals↗
PubMed2000

Genetic and biochemical analysis of brown eye mutation in Drosophila nasuta nasuta and Drosophila nasuta albomicans.

By analyzing the progeny of crosses involving brown eye mutants and the wild types in two members of Drosophila nasuta subgroup namely D. n. nasuta and D. n. albomicans we could show that the mutant gene is recessive, located in the chromosome 2 and the alleles of this gene are present at different loci. A study of fitness in the eye color mutants in comparison with the wild types revealed that D. n. nasuta mutant has higher viability at both 25+/-1 degrees C and ambient temperatures; while D. n. albomicans mutant has faster rate of development only at 25+/-1 degrees C. Quantitative analysis of eye pigments in the mutants revealed that there is biosynthesis of both pteridines and xanthommatins unlike in bw/bw of D. melanogaster, where only xanthommatins are synthesized. In both the species, the pteridine quantities in mutants are similar; whereas xanthommatin quantity in bw(n)/bw(n) is 10 times higher than that of bw(a)/bw(a). Further, the F1 progeny of intraspecific crosses (wild type X mutant) are found to have high amounts of pteridine, even when compared with parental wild type.

Animals↗
PubMed1988

Location of an autosomal factor causing sterility in Drosophila mojavensis males carrying the Drosophila arizonensis Y chromosome.

Drosophila mojavensis males whose Y chromosome is replaced by the Y of D. arizonensis, have immotile sperm. Sperm motility is restored if one member of the fourth autosome pair is also replaced by an arizonensis homologue. We present evidence that the effect of the fourth chromosome is due to a single Mendelian factor and map this factor relative to the two markers available for this chromosome. This is an essential first step towards understanding the nature of the incompatibility between the arizonensis Y chromosome and the mojavensis fourth chromosome responsible for this type of post-zygotic isolation between these closely related species.

Animals↗
PubMed1991

The evolutionary history of D. buzzatii. XXII. Chromosomal and genic sterility in male hybrids of Drosophila buzzatii and Drosophila koepferae.

The genetic basis of sterility in F1 male hybrids of Drosophila buzzatii and D. koepferae has been investigated in two steps. (1) By successive backcrossing of hybrid females to either parental species. (2) By assessment of the effects on male fertility of selected segments of polytene chromosomes from the donor species on a background entirely derived from the recipient species. The length of introgressed segments producing sterility was progressively reduced through repeated backcrosses. This procedure sometimes led to an approximate mapping of major genes of hybrid sterility (genic sterility) on the polytene chromosome map. At other times it was found that sterility was produced only when the introgressed segment exceeded a certain threshold size (chromosomal sterility). The contribution of the autosomes to hybrid sterility seems to be mainly of the chromosomal type. The evidence concerning the X chromosome is equivocal. No fertile males were found following introgression with any of the investigated segments of this chromosome. These results are compatible both with the presence of at least six major genes of hybrid sterility (genic sterility) and with the existence of a rather small threshold size for the chromosome segments producing sterility (chromosomal sterility). The role of the Y chromosome was not investigated in this study.

Animals↗
PubMed1991

Sterility of male and female hybrids of Drosophila virilis and Drosophila lummei.

The sterility of interspecific hybrids between the sibling species Drosophila virilis and D. lummei was tested in reciprocal F1s and different second generation combinations of cytoplasm, sex chromosomes and autosomes. Males with motile sperm and females with at least one mature egg were scored as fertile. When D. virilis was the mother, about 5 per cent of the F1 male progeny was sterile, the reason being that the X of D. virilis was weakly incompatible with the heterozygous second, fourth and fifth chromosomes. The F1 males carrying the X chromosome of D. lummei were all fertile. The X chromosome of D. lummei, and in particular its species-specific double inversion In(1)a + b, nevertheless caused sterility in 70 per cent of males in the presence of homozygous autosomes of D. virilis. Sterility was rare among the females, although some weakly disadvantageous X versus autosome and autosome versus autosome interactions were detected. The male and female hybrid sterilities were based on different genetic systems. The results emphasize the central role of the X chromosome in hybrid male sterility.

Animals↗
PubMed1976

[Sensitivity of the ova of Drosophila (Drosophila melanogaster, Meig.) to the lethal action of ultraviolet rays. iv. Survival of embryos irradiated at the segmentation stage].

During the early segmentation stage, Drosophila eggs are very resistant to U.V. light. At that time their survival curve presents a plateau. This inflection of the curve cannot be explained by a restoration mechanism, nor by differential sensitivity of mitotic phases. It must be ascribed to the presence in the irradiated population of eggs that have been retained and deposited after the beginning of embryogenesis. Many reasons permit to relate the decline in resistance of the eggs to U.V. light during segmentation to the decrease in the DNA content in the cytoplasm.

Animals↗
PubMed1977

Chromosomal basis of dosage compensation in Drosophila. IX. Cellular autonomy of the faster replication of the X chromosome in haplo-X cells of Drosophila melanogaster and synchronous initiation.

[(3)H]Thymidine labeling patterns have been examined in gynandric mosaic salivary glands of drosophila melanogaster. The Ring-X stock, R(1) w(ve)/In(1)dl 49, l (1) J1 y w lz(s), was used for this purpose. 365 labeled XX2A and 40 labeled XO2A nuclei were obtained from a total of 624 nuclei in nine pairs of mosaic salivary glands. It was observed that in all but those nuclei which had DD, 1C, and 2C patterns, the X chromosome of the XO2A nuclei always had fewer sites labeled than the X chromosomes of the XX2A nuclei, for a given pattern of the autosomes in either sex. Such asynchronous labeling of the X chromosome in the XO2A (male) nuclei was observed regardless of the proportion of the XO2A cells (2.0-73.7 percent), in the mosaic glands. Moreover, while the frequency of [(3)H]thymidine labeling for all of the 39 replicating units except the two late replicating sites (3C and 11A) in the X chromosome of the XO2A nuclei, was consistently lower than in the X chromosome of the XX2A nuclei, the mean number of grains on the X chromosome was relatively (to autosomes) similar in both XX2A and XO2A cells. The results, therefore, suggest that, as in XY2A larval glands, the X chromosome in the XO2A cells also completes the replication earlier than autosomes and that the XO2A nuclei show cellular autonomy with respect to the early replication of the X chromosome, like its counterpart, RNA transcription. Absence of the asynchrony during the initial phase (DD-2C) further completes the replication earlier but that the rate of replication of its DNA is possibly faster, and (b) that there might be a common regulation with respect to the initiation of replication of different chromosomes in a genome.

Animals↗
PubMed1982

Genic variation in abundant soluble proteins of Drosophila melanogaster and Drosophila pseudoobscura.

Genic variation was surveyed for 20 proteins of Drosophila melanogaster and 18 proteins of D. pseudoobscura. Analysis was by extraction and one-dimensional polyacrylamide gel electrophoresis under nondenaturing conditions, followed by staining with Coomassie Brilliant Blue to detect soluble proteins present in relatively large amounts ("abundant soluble proteins"). D. melanogaster was polymorphic for 65% of its protein loci and an individual was heterozygous for 10% of its loci. The respective figures for D pseudoobscura were 61% and 11%. These estimates of genic variation fall between previously published estimates obtained for these species by one-dimensional electrophoresis of soluble enzymes and those obtained by two-dimensional electrophoresis of solubilized abundant proteins. However, variation for both species could be strongly partitioned between loci, on the basis of tissue and stage expression of the proteins. The results are discussed with respect to their bearing on the possibility that abundant proteins constitute a distinct class of proteins less polymorphic than soluble enzymes.

Alleles↗
PubMed1992

An empirical test of the meiotic drive models of hybrid sterility: sex-ratio data from hybrids between Drosophila simulans and Drosophila sechellia.

Recently, there has been much discussion regarding the hypothesis that divergence of meiotic drive systems in isolated populations can generate the patterns of reproductive isolation observed in animal hybridizations. One prediction from this hypothesis is that the sex ratio of hybrids with heterospecific sex chromosomes should greatly deviate from the Mendelian expectation of 50% female. From sex-ratio data in our Drosophila hybridization studies, we find no such deviation: the sex ratio of offspring of males with introgressed heterospecific Y chromosomes with various autosomal backgrounds does not differ from that of the pure species. We also discuss other aspects of the current meiotic drive models.

Animals↗
PubMed1996

A genome-wide survey of hybrid incompatibility factors by the introgression of marked segments of Drosophila mauritiana chromosomes into Drosophila simulans.

In hybrids between Drosophila simulans and D. mauritiana, males are sterile and females are fertile, in compliance with HALDANE's rule. The genetic basis of this phenomenon was investigated by introgression of segments of the mauritiana genome into a simulans background. A total of 87 positions throughout the mauritiana genome were marked with P-element insertions and replicate introgressions were made by repeated backcrossing to simulans for 15 generations. The fraction of hemizgyous X chromosomal introgressions that are male sterile is approximately 50% greater than the fraction of homozygous autosomal segments. This result suggests that male sterility factors have evolved at a higher rate on the X, but chromosomal differences in segment length cannot be ruled out. The fraction of homozygous autosomal introgression that are male sterile is several times greater than the fraction that are either female sterile or inviable. This observation strongly indicates that male sterility factors have evolved more rapidly than either female sterility or inviability factors. These results, combined with previous work on these and other species, suggest that HALDANE's rule has at least two causes: recessivity of incompatibility factors and differential accumulation of sterility factors affecting males and females.

Animals↗
PubMed1980

Distinctions among allelic variants associated with chromosome 3 inversions in Drosophila pseudoobscura and Drosophila persimilis.

Efforts were made to discriminate new genetic variants among electrophoretic alleles that are associated with chromosome 3 inversions of Drosophila pseudoobscura and D. persimilis. Apparent genetic similarities for electrophoretic alleles between these two species and among the common inversions they carry were reexamined by altering gel concentration and buffer pH. At the amylase locus, the 1.09 electrophoretic allele could be further separated into two allelic classes that differentiated the WT and KL arrangements. Similarly, the 0.84 electrophoretic allele was divided into two allelic classes, one characteristic of the Santa Cruz phylad arrangements, TL and SC, and the other found in strains of the Standard phylad arrangements and CH. Uncommon amylase alleles proved to be different alleles in the two species. No new allelic variants, however, could be found among strains with the amylase 1.00 allele, the commonest allele in the Standard phylad of both species. No major new allelic variation was detected for acid phosphatase-3 and larval protein-10 that revealed any further differentiation among species or inversions. Variation at all three loci in strains of the Bogota population remained genetically similar to variation in strains of mainland D. pseudoobscura.

Amylases↗
PubMedDate not supplied

Stable Drosophila buzzatii-Drosophila koepferae hybrids.

Previous experiments discovered high rates of chromosomal rearrangements in the progeny of males containing a telomeric segment of Drosophila koepferae in a D. buzzatii genetic background (segmental males). We have performed similar experiments, designed to test whether this chromosomal instability could be explained by a phenomenon similar to P-M hybrid dysgenesis or, alternatively, by a generalized telomeric effect. However, the results obtained have not allowed us to fully characterize this process, because we have not observed chromosomal rearrangements in the progeny of the putative unstable males. Our results suggest that chromosomal instability is independent of the introgressed fragment. A reasonable hypothesis to explain these results is that mutator factors are occasionally introduced by the hybridization. The effect of sampling, caused by the fact that only a small region is introgressed in a particular line, may explain why only some hybridizations lead to instability.

Animals↗
PubMed1986

Transient expression of Drosophila melanogaster rDNA promoter into cultured Drosophila cells.

Recombinant plasmids that carry the bacterial CAT gene under the transcriptional control of the D. melanogaster rDNA promoter have been introduced by transfection into cultured Schneider II Drosophila cells and their template activity followed at the RNA and protein level. While no CAT enzyme activity is measurable 48 hrs after transfection, high levels of hybrid rRNA-CAT transcripts that originate at the authentic rRNA start site are detected by S1 mapping analysis. The interval -180/+34 of a rDNA transcriptional unit is sufficient to ensure faithful polymerase I transcription. However, the presence of a complete NTS (non transcribed spacer) region greatly enhances the transcriptional activity of exogenously added rDNA templates. Competition experiments between constructs carrying different amounts of NTS sequences indicate that spacer segments confer a transcriptional advantage efficiently attracting necessary transcription factors and/or polymerase I molecules.

Acetyltransferases↗
PubMed1993

Two Drosophila retrotransposon gypsy subfamilies differ in ability to produce new DNA copies via reverse transcription in Drosophila cultured cells.

Plasmid DNA constructs containing 5' end truncated retrotransposon gypsy were introduced into Drosophila cultured cells. Appearance of new complete DNA copies with reconstructed via reverse transcription 5'LTR were detected by PCR after transient expression and by Southern blot analysis of genome DNA of stably transformed cells. Two gypsy subfamilies supposed to be different in transpositional activity were analyzed in terms of their ability to produce new DNA copies via reverse transcription in D. hydei cultured cells. It was demonstrated that both gypsy variants undergo retrotransposition but with different efficiency.

Animals↗
PubMed1994

Cloning the Drosophila homolog of the xeroderma pigmentosum complementation group C gene reveals homology between the predicted human and Drosophila polypeptides and that encoded by the yeast RAD4 gene.

A human xeroderma pigmentosum group C (XPC) cDNA has been previously isolated by functional complementation (Legerski and Peterson, Nature, 359, 70-73, 1992). Sequence analysis did not reveal protein motifs which might suggest a possible biochemical function for the putative XPC protein. In order to identify functional domains in the translated XPC sequence the homologous gene from Drosophila melanogaster, designated XPCDM, was cloned by DNA hybridization. Sequence analysis of an apparently full-length cDNA revealed an open reading frame which can encode a predicted polypeptide of 1293 amino acids. Significant homology of the C-terminal 346 amino acids with both the human XPC and Saccharomyces cerevisiae Rad4 protein sequences is observed, suggesting that these proteins are functional homologs.

Amino Acid Sequence↗
PubMedDate not supplied

Population genetics of Mexican Drosophila. I. Chromosomal variation in natural populations of Drosophila pseudoobscura from Central Mexico.

Drosophila pseudoobscura populations of Central Mexico are chromosomally highly polymorphic. Five gene arangements in the third chromosome are endemic, including the two newly described in the present article. The phylogenetic tree of the gene arrangements known in the species is shown in Figure 1. The ones found in Central Mexico all belong to the Santa Cruz "phylad", while in the northern part of the species area both Santa Cruz and Standard phylads are widespread. Some inferences concerning the evolutionary history of the species are presented.

Animals↗
PubMed1991

The structure of the Adh locus of Drosophila mettleri: an intermediate in the evolution of the Adh locus in the repleta group of Drosophila.

Members of species of the mulleri and hydei subgroups of the repleta group of Drosophila have duplicate Adh genes. The Adh regions of D. mojavensis, D. mulleri, and D. hydei contain three genes--a pseudogene, Adh-2, and Adh-1--arranged 5' to 3'. To understand the evolution of the triplicate Adh structure, we have cloned and sequenced the Adh locus of D. mettleri. This region consists of a 5' pseudogene and a 3' functional Adh gene. On the basis of the structure and nucleotide sequence comparisons of Adh genes of D. mettleri and other species, we propose that an initial duplication of the ancestral Adh gene generated two Adh genes arranged in tandem. The more 5' Adh gene became a pseudogene, while the more 3' gene remained functional through all the developmental stages. A second duplication of this 3' gene resulted in Adh regions with three genes--a pseudogene, Adh-2, and Adh-1.

Alcohol Dehydrogenase↗